THERE IS NO NEED TO WASTE PAINT. AND IF YOU DON'T PUT OUT PAINT YOU CANNOT PAINT. YOU WILL NEVER LEARN TO MIX, TO MAKE GREYS, ETC,
Everyone has a system. My system is to have both a holding and a mixing area. I hold my paint in the small Masterson Sta Wet palette without paper when doing plein air. I take from there and mix on a neutral gray glass surface. Paint , if kept moist, lasts for weeks in the Sta Wet.
|Small Sta-Wet on Coulter Art Box system
In my studio I hold my paints in the large, 12x16 Sta Wet palette and take from there to mix on glass .
|Studio large Sta Wet beside glass mixing area
If and when the paints in my palette are starting to dry, its getting too messy, or I am just not going to be using them I scrape off the paint and place into a jar with a air-tight lid . When mixed they usually create a gray of some value. I adjust the value with titanium white ( usually fluid) then leave or change the grey to a hue normally using Goldens Fluids with their high pigment content. I then put some on the lid so I know what the dried colour and value will be .
|Palette scrapings mixed together
|mixed produces a grey that is adjusted for value with white
|then adjusted for hue as needed
I can have up to 12 to 20 jars at anyone time each with a known hue and value. These are invaluable for areas like skies that I have to create negatively and often have to come back into to correct. No mixing needed - I have a jar with the colour and value required. Has made my large acrylic pieces so my easier and NO WASTE.
When the jars empty there is always a bit on the bottom and sides . Let that air dry then soak in water a few days and that will peel out as a piece of colored plastic leaving a clean jar.
|Soaking in water
|Polymer plastic lifts out after soaking to leave a clean jar
I paint half the year in BC and half in Ontario. The jars are thus unused for up to 6 months. If I have done a good job of cleaning the tops to create a good seal the paint is still usable.